Cycling mechanism

ABSTRACT

A pressure fluid operated motor moves a predetermined distance in one direction and then a predetermined distance in another direction. The activating pressurized fluid flows through an expansible chamber having a pressure relief valve to the motor. A predetermined volume of fluid must enter the expansible chamber before sufficient pressure is built up to unseat the relief valve and allow pressure fluid to flow to the motor. This results in a time delay between each change in direction of movement of the motor.

United States Patent Smith [451 Sept. 26, 1972 CYCLING MECHANISM FOREIGNPATENTS OR APPLICATIONS Inventor: Charles Smith. York, 379,979 9/1932Great Britain ..91/219 [73] Assignee: Ams chalmers Manufacturing 443,4102/1936 Great Britain ..91/219 puny Mllwaukee Primary Examiner-Paul E.Maslousky [22] Filed: Dec. 2, 1970 Attorney-John P. Hines, Robert B.Benson and [211 pp No; 94,446 Charles L. Schwab [57] ABSTRACT U.S. Cl- Apressure operated motor moves a predete 1 91/412 mined distance in onedirection and then a predeter- [51] Int. Cl. ..F0ll 1/20, F01] 25/06mined distance in another direction. The activating [58] Field of Search..91/219, 245, 218,307, 412, pressurized fluid flows through anexpansible chamber 91/275; 92/605 having a pressure relief valve to themotor. A

predetermined volume of fluid must enter the expansi- [56] ReferencesCited ble chamber before sufficient pressure is built up to unseat therelief valve and allow pressure fluid to flow UNITED STATES PATENTS tothe motor. This results in a time delay between 3,046,951 7/1962Freeborn ..91/275 each mange mmmem the 3,186,309 6/1965 Killebrew..91/412 4 Claims, 2 Drawing Figures CYCLING MECHANISM This inventionpertains in general to fluid cycling mechanisms and more particularly tosuch a mechanism having an intermediate time delay.

Cycling mechanisms are used in many different manufacturing operationssuch as, for instance, grinding machines and automatic welding machines.The machine is operated in one direction for a predetermined period oftime and then comes to a stop. A delay in operation then takes place fora predetermined period of time. After the delay period the machineoperates in the opposite or a different direction, and at the end ofthat stroke an additional time delay takes place.

It is the general object of this invention to provide a cyclingmechanism with intermediate time delay which is relatively inexpensiveand of simplified construction and operation.

A more specific object of the subject invention is to provide afluid-operated cycling mechanism wherein the amount of time delaybetween alternate operations of the fluid motor is adjustable.

An additional object of the subject invention is to provide afluid-operated cycling mechanism of the hereinbefore described type withmeans to automatically shift the mechanism control valve at the end ofeach motor operation to initiate delivery of pressure fluid for the nextmotor operation in a different direction.

These and other objects of the subject invention will become more fullyapparent as the following description is read in light of the attacheddrawing wherein FIG. 1 is a cross sectional side elevation of afluidoperated cycling mechanism constructed in accordance with theinvention and FIG. 2 is an end view of FIG. 1

Referring to the attached drawing, the cycling mechanism of thisinvention is shown contained in a single housing generally designated 6.A fluid motor herein shown for purposes of illustration as a piston 7 isreciprocably contained in a cylindrical chamber 8 within the housing 6.The piston 7 divides the cylinder into motor chambers 9 and 11. Pistonrods 12 and 13 are connected to opposite ends of the piston 7 andextendwithout the housing 6. These piston rods provide the connecting means tothe element or elements that are to be cycled.

An additional elongated cylindrical chamber generally designated 14 isprovided in the housing 6. A free-moving piston 16 is slidably containedwithin the cylindrical chamber 14 and divides such chamber into a pairof expansible fluid chambers 17 and 18. Means are provided toselectively adjust the extent of movement of the piston 16 in chamber14. To this end, as hereinshown for purposes of illustration, a pair ofstops l9 and 21 are threadably received in internally threaded boresprovided through the housing 6 into the expansible chambers 17 and 18.The adjustable stops may be turned in or out in the threaded bores tolimit the extent of movement of the piston 16.

A reversing valve is also provided in the housing 6. This reversingvalve is composed of a cylindrical chamber 22 having a spool 23 slidablycontained therein. The spool 23 is provided with a pair oflongitudinally spaced annular lands 24 and 26. A pressure fluid inletport 27 is connected to the control valve cylinder 22 at a pointintermediate the lands 24 and 26. A fluid pressure source in the form ofa pump 30 is connected to the inlet port 27. A pair of combinationsupply and exhaust passages 28 and 29 connect the reversing valvechamber 22 to the expansible chambers 17 and 18 respectively.

Fluid chambers 31 and 32 are provided on opposite ends of the reversingvalve chamber 22 in alignment therewith. A reduced portion of the spool23 extends into each chamber 31 and 32, and each portion is providedwith a piston 33 and 34 respectively. The remote ends of pistons 33 and34 are exposed to pressurized fluid through passageways 36 and 37connected to the supply port 27. Each of these passageways 36 and 37 isalso connected to the system sump by means of passageways 38 and 39extending without the housing 6. In this instance it is intended thatthe housing 6 will be submerged in fluid, and, therefore, the exteriorof the housing is the system sump. Stoppers 41 and 42 are aligned withthe passageways 38 and 39 respectively. Each stopper 41 and 42 isconnected respectively to the piston rods 12 and 13 for movementtherewith. When a stopper engages the housing at a passageway outlet,that passageway is isolated from the system sump, and an increasedpressure occurs in the cylinder chamber 31 or 32 connected to thatpassageway.

Chamber 18 is connected to chamber 11 in one direction by means ofpressure relief valve 43 and in the opposite direction by means of checkvalve 44. Chamber 17 is connected to chamber 9 in one direction by meansof pressure relief valve 46 and in the opposite direction by means ofcheck valve 47. The pressure relief valves 43 and 46 permit pressurizedfluid to flow from chambers 18 and 17 into chambers 11 and 9respectively upon attainment of a predetermined fluid pressure inchambers 18 and 17. When fluid is flowing from chamber 18 to chamber 11, fluid is exhausting through check valve 47 from chamber 9 to chamber17.

The operation of the cycling mechanism is as follows. In the positionshown in the drawing, the piston 7 is about to move to the left. Fluidfrom the supply port 27 passes through the chamber 22 through passageway29 into expansible chamber 18. Since the piston 16 has moved to the leftagainst the stop 19, fluid will fill the expansible chamber 18 andincrease in pressure until it exceeds the predetermined pressurerequired to unseat the pressure relief valve 43. Fluid then enters thechamber 11 and moves the piston to the left. At the end of the powerstroke of piston 7 a stopper 42 will cover the passageway 39. This willcause an increase in pressure to the right of the piston 34 on the rightend of the spool 23. As the pressure increases, the spool 23 will 7 moveto the left causing the lands 24 and 26 to move to the left of thepassageways 28 and 29. Pressure fluid will then pass through chamber 22and passageway 28 into expansible chamber 17. As the fluid fillsexpansible chamber 17, the piston 16 will move to the right until itcontacts stop 21. At this point the pressure in expansible chamber 17will increase to the point where it exceeds the pressure required tounseat pressure relief valve 46 and will then enter chamber 9, movingthe piston 7 to the right. As the piston 7 moves to the right, fluid inchamber 11 will pass through check valve 44 and expansible chamber 18,passageway 29, and out exhaust port 48. When the piston 7 has reachedthe end of its stroke to the right, the stopper 41 will close off thepassageway 38 causing an increase in pressure to the left of the piston33 at the left end of spool 23. This will cause the spool to move to theright, and the cycle will repeat itself.

From the above description it can be seen that a very simplified andinexpensive cycling mechanism has been provided. This mechanism permitsadjustment of the power stroke as well as adjustment of the timeinterval between each power stroke.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A pressure fluid operated cycling mechanism having a pressure fluidsource and a fluid sump comprising: a reversible fluid motor having apower operating cycle; a cylinder having a piston slidable thereindividing said cylinder into separate expansible fluid chambers; stopmeans associated with said chambers limiting the extent of movement ofsaid piston; fluid pressure responsive means connecting said motor inpressure fluidcommunication with one of said expansible chambers aftersaid piston has engaged said stop means and the fluid pressure in saidone of said chambers has exceeded a predetermined level; a reversingvalve having a spool selectively movable to permit and interrupt theflow of fluid to said chambers, opposite sides of said spool beingexposed to the same fluid pressure whereby the net fluid force tendingto move said spool is zero; and valve spool control means operable toincrease the fluid pressure on one side of said spool relative to theother side when said motor has reached the end of an operating cycle tomove said spool and interrupt the flow of pressure fluid to said one ofsaid chambers and deliver pressure fluid to the other of said chambers.

2. The cycling mechanism set forth in claim 1 wherein said stop meansare adjustable to selectively change the extent of movement of saidpiston.

3. The cycling mechanism set forth in claim 1 wherein the pressure fluidconnected to opposite sides of said spool is also connected to sump andwherein said valve spool control means selectively and altematelyinterrupts the connection to sump on one side of said spool.

4. The cycling mechanism set forth in claim 3 wherein said reversiblefluid motor is a reciprocating fluid motor with oppositely extendingpiston rods and said valve spool control means is connected to saidpiston rods.

1. A pressure fluid operated cycling mechanism having a pressure fluidsource and a fluid sump comprising: a reversible fluid motor having apower operating cycle; a cylinder having a piston slidable thereindividing said cylinder into separate expansible fluid chambers; stopmeans associated with said chambers limiting the extent of movement ofsaid piston; fluid pressure responsive means connecting said motor inpressure fluid communication with one of said expansible chambers aftersaid piston has engaged said stop means and the fluid pressure in saidone of said chambers has exceeded a predetermined level; a reversingvalve having a spool selectively movable to permit and interrupt theflow of fluid to said chambers, opposite sides of said spool beingexposed to the same fluid pressure whereby the net fluid force tendingto move said spool is zero; and valve spool control means operable toincrease the fluid pressure on one side of said spool relative to theother side when said motor has reached the end of an operating cycle tomove said spool and interrupt the flow of pressure fluid to said one ofsaid chambers and deliver pressure fluid to the other of said chambers.2. The cycling mechanism set forth in claim 1 wherein said stop meansare adjustable to selectively change the extent of movement of saidpiston.
 3. The cycling mechanism set forth in claim 1 wherein thepressure fluid connected to opposite sides of said spool is alsoconnected to sump and wherein said valve spool control means selectivelyand alternately interrupts the connection to sump on one side of saidspool.
 4. The cycling mechanism set forth in claim 3 wherein saidreversible fluid motor is a reciprocating fluid motor with oppositelyextending piston rods and said valve spool control means is connected tosaid piston rods.